Biology 101

Cards · 53

Homeostasis

The maintenance of a stable, relatively constant internal environment within an organism.

Cell Theory

The principle that all living things are composed of cells, the cell is the basic unit of life, and all cells arise from pre-existing cells.

Prokaryote

A single-celled organism that lacks a nucleus and membrane-bound organelles.

Eukaryote

An organism whose cells contain a distinct, membrane-bound nucleus and specialized organelles.

Plasma Membrane

A selectively permeable phospholipid bilayer that surrounds a cell and regulates what enters and exits.

Phospholipid

A lipid molecule with a hydrophilic phosphate head and two hydrophobic fatty acid tails, forming cell membranes.

Nucleus

A membrane-bound organelle in eukaryotic cells that encloses and protects genetic material (DNA).

Ribosome

A cellular structure composed of RNA and protein that synthesizes proteins by translating mRNA.

Mitochondrion

An organelle that generates most of the chemical energy (ATP) needed to power biochemical reactions.

Chloroplast

A plant cell organelle that contains chlorophyll and carries out photosynthesis.

Endoplasmic Reticulum

A network of membranous tubules involved in protein synthesis (rough ER) and lipid synthesis (smooth ER).

Golgi Apparatus

An organelle that modifies, sorts, and packages proteins and lipids for storage or transport out of the cell.

Diffusion

The net movement of particles from an area of higher concentration to an area of lower concentration.

Osmosis

The passive diffusion of water molecules across a selectively permeable membrane.

Active Transport

The movement of substances across a cell membrane against their concentration gradient, requiring cellular energy (ATP).

ATP (Adenosine Triphosphate)

The primary energy carrier molecule used by cells to perform cellular work.

Enzyme

A biological catalyst, usually a protein, that speeds up chemical reactions by lowering the activation energy.

Active Site

The specific region of an enzyme where substrate molecules bind and undergo a chemical reaction.

Substrate

The specific reactant molecule upon which an enzyme acts.

Denaturation

The process where a protein loses its native shape and function due to extreme heat or pH changes.

Photosynthesis

The metabolic pathway by which autotrophs convert light energy, carbon dioxide, and water into glucose and oxygen.

Cellular Respiration

The metabolic process that breaks down glucose in the presence of oxygen to produce ATP, water, and carbon dioxide.

Glycolysis

The anaerobic breakdown of one glucose molecule into two pyruvate molecules, yielding a net of two ATP.

Krebs Cycle

A series of aerobic biochemical reactions inside mitochondria that oxidize acetyl-CoA into carbon dioxide, producing electron carriers and ATP.

DNA (Deoxyribonucleic Acid)

A double-stranded nucleic acid containing the genetic instructions used in the development and functioning of organisms.

Nucleotide

The monomer of nucleic acids, consisting of a nitrogenous base, a five-carbon sugar, and at least one phosphate group.

Base Pairing Rule

The complementary pairing of nitrogenous bases in DNA: adenine with thymine (A-T) and guanine with cytosine (G-C).

Gene

A specific sequence of DNA nucleotides that codes for a functional RNA or protein product.

Chromatin

The complex of DNA and histone proteins found inside the eukaryotic nucleus that condenses to form chromosomes.

Chromosome

A organized structure of DNA and protein that carries genetic information from one generation to the next.

DNA Replication

The biological process of producing two identical replicas of DNA from one original DNA molecule.

Transcription

The enzymatic synthesis of an RNA molecule from a complementary DNA template strand.

Translation

The cellular process where genetic code carried by mRNA is decoded by ribosomes to assemble a polypeptide chain.

Codon

A sequence of three consecutive nucleotides in mRNA that specifies a single amino acid or a termination signal.

Mutation

A permanent change in the nucleotide sequence of the genome of an organism.

Mitosis

A type of eukaryotic cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent.

Cytokinesis

The division of the cytoplasm into two daughter cells following nuclear division.

Meiosis

A specialized cell division that reduces chromosome number by half, producing four genetically diverse haploid gametes.

Haploid

A cell containing a single set of unpaired chromosomes (n), typical of gametes.

Diploid

A cell containing two complete sets of chromosomes (2n), one inherited from each biological parent.

Allele

One of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.

Genotype

The complete set of genes or alleles possessed by an organism.

Phenotype

The observable physical or biochemical characteristics of an organism, determined by genotype and environment.

Homozygous

Having two identical alleles for a particular gene (e.g., AA or aa).

Heterozygous

Having two different alleles for a particular gene (e.g., Aa).

Natural Selection

The process whereby organisms better adapted to their environment tend to survive and produce more offspring.

Evolution

A change in the heritable characteristics of biological populations over successive generations.

Adaptation

An inherited characteristic that enhances an organism's ability to survive and reproduce in a specific environment.

Speciation

The evolutionary formation of new and distinct biological species from an ancestral population.

Ecosystem

A biological community of interacting organisms and their physical abiotic environment.

Trophic Level

The hierarchical position that an organism occupies in a food chain (e.g., primary producer, primary consumer).

Autotroph

An organism capable of synthesizing its own food from inorganic substances using light or chemical energy.

Heterotroph

An organism that cannot synthesize its own food and must obtain nutrients by consuming other living organisms.